Heat shield panels and combustion chamber liners used in gas turbine engines usually have hundreds of effusion holes distributed in a non-symmetrical pattern and having varying directional vectors. Current methods for drilling such hole patterns include the use of conventional CAD/CAM systems and pulsed laser drilling machines having five axes of motion.
Conventional CAD/CAM systems are typically used to determine a hole drilling sequence for hole patterns based on the shortest distance between the entry point of each hole. CAD/CAM systems do not take into account the directional vector of each hole and also do not consider the kinematics of the multi-axis drilling machine during sequencing. Therefore, the drilling sequence may not be truly optimized. For example, even though the distance between the entry points of two holes within a hole pattern may be short, the fact that they have different directional vectors may result in relatively large displacements required by some axes of the drilling machine. Depending on the configuration of the drilling machine, this can lead to relatively long, irregular and unpredictable travel times between holes of the hole pattern. Further, the time required for the axes to travel between two consecutive holes can be longer than the interval between two consecutives pulses of the laser. Therefore, depending on the firing frequency of the laser, the shutter may have to be closed and re-opened between consecutive holes in the sequence. Evidently, this can lead to an unduly long cycle time for drilling the hole pattern.
Accordingly, there is a need to provide a method for drilling holes from a hole pattern in reduced time.